Butyl rubber compounds comprising a three component mixed modifier system

Abstract

Rubber compounds containing a halobutyl elastomer, at least one additional elastomer, a mineral filler and at least a three component mixed modifier system comprising a silane compound, a phosphine compound and an additive containing at least one hydroxyl group and a functional group containing a basic amine. A process for preparing the compounds is also disclosed. The compounds are particularly useful in tire treads and exhibit improved processability, traction, rolling resistance and wear properties.

1. A rubber compound comprising a halobutyl elastomer, at least one additional elastomer, a mineral filler, and an at least three component mixed modifier system comprising a silane, a phosphine, and an additive comprising at least one hydroxyl group and a functional group comprising a basic amine. 
     
     
       2. The rubber compound according to  claim 1 , wherein the halobutyl elastomer comprises a halogenated copolymer of at least an isoolefin and a conjugated diolefin. 
     
     
       3. The rubber compound according to  claim 2 , wherein the isoolefin comprises isobutylene and wherein the conjugated diolefin comprises isoprene. 
     
     
       4. The rubber compound according to  claim 1 , wherein the halobutyl elastomer comprises a halogenated terpolymer of an isoolefin, a conjugated diolefin, and a vinyl aromatic monomer. 
     
     
       5. The rubber compound according to  claim 4 , wherein the isoolefin comprises isobutylene, the conjugated diene comprises isoprene and the vinyl aromatic monomer comprises p-methylstyrene. 
     
     
       6. The rubber compound according to  claim 1 , wherein the additional elastomer comprises BR, SBR, NBR, NR, ENR or mixtures thereof. 
     
     
       7. The rubber compound according to  claim 1 , wherein the mineral filler comprises silica. 
     
     
       8. The rubber compound according to  claim 1 , wherein the silane comprises an aminosilane or a sulphur-containing silane. 
     
     
       9. The rubber compound according to  claim 8 , wherein the silane comprises bis[3-(triethoxysilyl)propyl]-monosulfane, bis[3(triethoxysilyl)propyl]disulfane, bis[3-(triethoxysilyl)propyl]trisulfane, bis[3(triethoxysilyl)propyl]tetrasulfane, bis[2-(triethoxysilyl)ethyl]-tetrasulfane, 3-(triethoxysilyl)propanthiol, or a mixture thereof. 
     
     
       10. The rubber compound according to  claim 1 , wherein the phosphine comprises trimethylphosphine, triethylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, or a mixture thereof. 
     
     
       11. The rubber compound according to  claim 1 , wherein the additive comprising at least one hydroxyl group and a functional group containing a basic amine comprises an aminoalcohol. 
     
     
       12. The rubber compound according to  claim 11 , wherein the aminoalcohol comprises mono ethanol amine (MEA), N,N-dimethylaminoethanol (DMAE), diethanolamine (DEA), dibutyl-aminoethanol (DBAE), methyldiethanolamine (MDEA), phenyldiethanolamine (PDEA), or a mixture thereof. 
     
     
       13. The rubber compound according to  claim 1 , wherein the phosphine is present in the range of 0.1 to 6.0 phr. 
     
     
       14. The rubber compound according to  claim 1 , wherein the additive comprising at least one hydroxyl group and a functional group containing a basic amine is present in the range of 0.1 to 6.0 phr. 
     
     
       15. The rubber compound according to  claim 1 , wherein the silane is present in the range of 0.1 to 15.0 phr. 
     
     
       16. The rubber compound according to  claim 1 , wherein the phosphine comprises triphenylphosphine and is present in the range of 0.1 to 6.0 phr, wherein the additive comprising at least one hydroxyl group and a functional group containing a basic amine comprises N,N-dimethylaminoethanol and is present in the range of 0.1 to 6.0 phr and wherein the silane comprises bis[3(triethoxysilyl)propyl]tetrasulfane and is present in the range of 0.1 to 15.0 phr. 
     
     
       17. The rubber compound according to  claim 1 , wherein the tan delta at 0° C. is greater than 0.325, wherein the tan delta at 60° C. is less than 0.120, wherein the abrasion volume loss (DIN) is less than 165 mm 3 , and wherein the tensile at break values are greater than 13.0 MPa. 
     
     
       18. A process for preparing a rubber compound comprising admixing a halobutyl elastomer, at least one additional elastomer, a mineral filler and an at least three component mixed modifier system comprising a silane, a phosphine and an additive comprising at least one hydroxyl group and a functional group comprising a basic amine. 
     
     
       19. The process according to  claim 18 , wherein the three components of the mixed modifier system, or portions thereof, are pre-mixed. 
     
     
       20. The process according to  claim 18 , wherein the three components of the mixed modifier system are admixed with a pre-mixed combination of the halobutyl elastomer, the at least one additional elastomer and the mineral filler.